A fundamental problem in sonar or radar imaging is that the echoes returned from the same object will differ depending on the aspect at which the sonar or radar radiatively scans the object. This is of special concern to a class of problems collectively named feature based navigation, in which a vessel, such as an ocean going ship, submersible platform, helicopter or airplane, or the like, compares echoes it receives to a pre-existing radar/sonar map to identify or update the vessel's location. If the aspect at which the map was generated differs from the aspect at which the vessel's radar/sonar scans, and all things being equal this would be so almost always, the correlation between the vessel's scan and the pre-existing map will be degraded. Another way to put this is that the point spread function relating radiative scatter from a point, to a detector, varies with aspect, so that, for example, a sonar detector will have a different point spread function at each aspect at which it can scan. Thus even echoes from the same object taken at identical distances from the detector, but at different aspects with respect to the detector, will have different signatures, and their correlation with one another, or with the same object's echo signature in an extant map, will be degraded.